The present invention relates to a magnetic head mounted in a hard-disk drive and more particularly to a magnetic head for use in a high recording density hard-disk drive.
A magneto-resistive magnetic head is used as a reproducing sensor in a high recording-density magnetic recording technology with a hard-disk serving as the main part thereof, being a part largely affecting the performance of the magnetic recording technology. While the recording density of the hard-disk drive is rapidly increasing, it has been impossible with the use of the conventional technology to implement a hard-disk drive having a sufficiently high recording density, and in particular, to implement a magneto-resistive magnetic head acting on an external magnetic field with a satisfactory sensitivity and sufficient output, at a reproducing part of the device, thereby obtaining sufficiently stable and excellent characteristics, so that it has been difficult to exhibit a function as a recording equipment.
It has recently known that a magnetoresistance of a multilayered film made up of ferromagnetic metal layers deposited one on top of the other with a nonmagnetic metal layer interposed therebetween, the so-called giant magnetoresistance, is large. When a magnetic head makes use of the magnetoresistance, use has thus far been made of the so-called CIP-GMR that is obtained when a current is passed in the in-plane direction of a multilayered film. Further, research has lately been carried out on a perpendicular current type giant magnetoresistance obtained when a current is passed in the direction of thickness of a multilayered film, the so-called CPP-GMR as well.
Examples of current technology are found in JP-A No. 304026/1993 (Patent document 1); JP-A No. 169026/1995 (Patent document 2); and JP-A No. 12649/1994 (Patent document 3).